2011 Volume 60 Issue 5 Pages 265-270
The films formed on boiler tube steels for thermal power plant in the simulated AVT (All Volatile Treatment) water at high temperature are analyzed by X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). In addition, the corrosion resistances of the films are evaluated using electrochemical techniques in the simulated AVT water added with chloride ions (Cl−).
The magnetite films formed on STB410 and STBA24 steels in the simulated AVT water at 598 K. The films show better corrosion resistances to Cl− at room temperature. It seems to be related with restraint of the magnetite crystal growth and improvement of the density.
On the other hand, the complex film, composed of Fe-oxides and Cr-oxides, is observed on SUS304 steel. Their corrosion resistance is lower than that of the film formed at room temperature. The film formed at high temperature should be unstable by the formation of local cell caused due to partial segregation of Cr.
